The present invention relates to a shrinking protective wrapping or film for protecting products, especially packages.
Protective wrappings or films are used for so-called bundle package lots such as bundle bags or sacks and similar packaging, as well as for pallet loads in order to protect packages. When protecting packages by means of, for instance, protective wrapping which is shrunk around the packages with a conventional technique such as heat-sealing which is the equivalent of heating and radiation sealing or radiation heating, in the currently used protective wrappings the inner surface thereof sticks to the packages being protected. The packages might easily be damaged when removing the protective wrapping later.
Efforts have previously been made to eliminate the above-noted problems by, for instance, placing a sheet of paper between the package and the protective wrapping which prevents the protective wrapping from sticking to the package. Another known solution is the so-called double wrapping arrangement in which the inner wrapping does not stick to the packages because it does not shrink under normal conditions. In this arrangement, the outer wrapping is conventional shrinking protective wrapping.
A drawback of both these arrangements is the complicated packaging method which is also uneconomical from the point of view of material consumption and the working time used in the packaging operation.
An arrangement is also known in which materials are selected either for the protective wrapping or the plastic bags being packaged, so that either the density of the protective wrapping material is smaller than the density of the plastic bag material, or the density of the plastic bag material is smaller than the density of the material of the protective wrapping. Even this type of solution has the drawback that the materials may stick together, despite the different densities thereof.
An arrangement is also known in which the protective wrapping is made of so-called combination film. The inner surface of this kind of combination film is, for instance, polypropylene. A drawback of this prior art solution is difficulty in carrying out and controlling the shrinking operation.